function toTop(_$) {
    var style = document.createElement('style')
    style.innerHTML = `.to-top{
        display: none;
        position: fixed;
        right: 30px;
        bottom: 103px;
        cursor: pointer;
        overflow: visible;
        z-index: 9990;
        width: 54px;
        height: 54px;
        line-height: 54px;
        color: #ffffff;
        text-align: center;
        /* background-image: url(/images/landing/homepage/new/icon/toTop.svg); */
        -webkit-background-size: 21px 22px;
        -moz-background-size: 21px 22px;
        background-size: 21px 22px;
        background-repeat: no-repeat;
        background-position: center;
        -webkit-transition: all 0.15s;
        -moz-transition: all 0.15s;
        -o-transition: all 0.15s;
        -ms-transition: all 0.15s;
        transition: all 0.15s;
        -webkit-box-shadow: 0 6px 16px 0 rgba(65, 80, 88, 0.16);
        box-shadow: 0 6px 16px 0 rgba(65, 80, 88, 0.16);
        border-radius: 50%;
        background-color: #7d8694;
        opacity: 0.3;
        -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=30)";
        filter: alpha(opacity=30);
    }`
    document.head.appendChild(style);
    var div = document.createElement("div");
    div.innerHTML = '<i class="fa fa-chevron-up" aria-hidden="true"></i>';
    div.className = 'to-top';
    document.body.appendChild(div);
    //滚动显示
    _$(window).scroll(function () {
        if (_$(window).scrollTop() > 100) {
            _$(div).fadeIn(300);
        }
        else {
            _$(div).fadeOut(100);
        }
    });
    //点击置顶
    div.onclick = function () {
        _$('html,body').animate({ 'scrollTop': 0 }, 500);
    }
}